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[PATCH] rtc: small documentation update
Rtc driver documentation update * Mention the max-user-freq control file. * Add missing header in example code. Signed-off-by: Jean Delvare <khali@linux-fr.org> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -44,8 +44,10 @@ normal timer interrupt, which is 100Hz.
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Programming and/or enabling interrupt frequencies greater than 64Hz is
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only allowed by root. This is perhaps a bit conservative, but we don't want
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an evil user generating lots of IRQs on a slow 386sx-16, where it might have
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a negative impact on performance. Note that the interrupt handler is only
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a few lines of code to minimize any possibility of this effect.
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a negative impact on performance. This 64Hz limit can be changed by writing
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a different value to /proc/sys/dev/rtc/max-user-freq. Note that the
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interrupt handler is only a few lines of code to minimize any possibility
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of this effect.
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Also, if the kernel time is synchronized with an external source, the
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kernel will write the time back to the CMOS clock every 11 minutes. In
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@ -81,6 +83,7 @@ that will be using this driver.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <linux/rtc.h>
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#include <sys/ioctl.h>
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#include <sys/time.h>
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